1. Field of the Invention
This invention relates to a method for producing a semiconductor device including semiconductor chips such as a pressure sensor by coating electrodes and wires with a thin film.
2. Description of the Related Art
A semiconductor chip such as a pressure sensor is mounted on an electronic part and is electrically connected to electrodes of the electronic part via wires. The wires and the electrodes are usually coated with a thin film not to be exposed, thereby preventing corrosion of the wires and the electrodes.
The thin film is deposited on the electronic part to coat the electrodes and the wires in a state in that only the semiconductor chip and a vicinal region around the chip is exposed from an opening portion of a mask member (frame) disposed on the electronic part. This is because the thin film must be prevented from being deposited on the other region of the electronic part than the exposed region, which has members to be electrically connected to external units.
Specifically, as shown in FIG. 11, in a pressure sensor assembly (semiconductor device), after a pressure sensor element 101 is installed in a resin-made housing 102, a wire 104 is bonded to a lead portion 103 insert-molded in the housing 102. Then, an organic deposition film is formed to coat the wire 104 and the lead portion 103 as indicated by a dotted line in FIG. 11. At that time, it is necessary to prevent the thin film from being deposited on the other region than the region where the sensor element 101 is mounted, because the other region (for instance, connector portion 102a) must provide electrical connection with external units.